Anemia Flashcards
RBC stucture and function
Anucleate cell
Cytoskeleton maintains shape as a biconcave disc, which allows for greater flexibility, transit through microvasculature
Contains mostly hemoglobin, the primary carrier molecule of oxygen and carbon dioxide
Survives in circulation for ~120 days, before clearance by splenic macrophages
Reticulocytes
Immature anucleate erythrocyte
Contains high concentration of rRNA, imparting a blue color
Normal retic count 0.5-1.5%
Not usually prominent on blood smear
Increased levels easily noted on blood smear, termed polychromasia
Nucleated RBCs
RBC precursor, also called a normoblast
Presence in adult peripheral blood is always abnormal
May indicate pathologically brisk erythropoiesis is occurring in the bone marrow
Senescence
Aged erythrocytes accrue membrane abnormalities
Recognized by splenic cord macrophages as RBCs transit the splenic sinuses
Ingested and destroyed
Anemia defined
Reduction in oxygen-carrying capacity of blood
Decreased number of RBCs
Decreased amount of hemoglobin per RBC
Symptoms: fatigue, dyspnea on exertion, faintness/lightheaded, headache
Anemia
Anemia
alone is not a diagnosis
Must examine underlying cause and mechanism to fully diagnose the disease
Peripheral blood smear
Microcytosis, macrocytosis, etc. assessed by cell size on smear
Hypochromasia assessed by size of the central zone of pallor (when wider than 1/3 the RBC width hypochromic)
Decreased production
Decreased stem cell production:
Aplastic anemia
Renal failure
Ineffective maturation of erythrocytes:
Defective hemoglobin synthesis
Defective DNA synthesis
Iron
Nutritional deficiency,
chronic disease
Heme group
Failures of porphyrin ring synthesis
Globin proteins
Hemoglobinopathies
Erythropoiesis
Production of red blood cells occurs in the bone marrow
Erythrocyte precursors derive from a pluripotent hematopoietic stem cell
Stimulated by erythropoietin produced by the kidney
Continually replicate to produce about 1010 RBCs per hour
